1. Field of the Invention
This invention pertains to a fixture for housing an electrical lamp with two electrical terminals. The invention specifically pertains to a mechanism for facilitating safe installation of the lamp into the light fixture.
2. Description of Related Art
The light fixtures of the related art are commonly known as floodlights. The Quartzlite.TM. Series G500 and G1500 sold by Appleton.RTM. Electric Company are commercially available floodlights. Floodlights are used in the outdoors for industrial, sporting or commercial settings where the light must be distributed with efficiency and control.
Floodlights have two basic components: a double-ended lamp for providing light and a light fixture for housing the lamp. The double-ended electrical lamp typically has a cylindrical, glass casing sealed at each end with an insulator surrounding an electrical terminal. A filament runs between the two terminals to deliver electrical current from one terminal to the other terminal. The interior of the casing is subjected to a vacuum or is filled with a non-combustible halogenic gas to prevent damage to the filament. The filament is typically made from tungsten.
The light fixture for the double-ended lamp comprises a housing with two sockets, each socket for receiving a respective end of the lamp. One of the sockets is usually biased by a spring toward the center of the fixture. To install a lamp in the fixture, one end of the lamp is inserted into a respective socket and the spring loaded socket is pushed against the bias of the spring to make room for the lamp to fit in the other socket. Once the lamp is disposed between the two sockets, the spring-loaded socket is released to allow the bias of the spring to bear the spring-loaded socket against the respective end of the lamp. As a result, the sockets firmly engage the terminals of the lamp. The sockets are each connected to an electrical circuit, so that current flows from the electrical circuit through the lamp to illuminate the filament when the fixture is energized.
It is well known in the art that when installing a lamp into the light fixture, all electricity to the fixture should be shut off. Written warnings to this effect are included with the floodlights that are commercially available. In the unforeseeable event that an installer were to ignore these warnings and attempt to install a lamp into such a fixture without shutting off the power, the installer could experience an electrical shock under the following limited circumstances. If the installer does not shut off the power to the light fixture and inserts one of the terminals of the lamp into an electrically live socket and then touches the other end of the lamp, the installer could experience an electrical shock. Moreover, if the installer first inserts an end of a lamp into the spring-loaded socket which is electrically live, he may be tempted to place his thumb on the other end of the lamp to urge the lamp outwardly against the bias of the spring-loaded socket, thereby subjecting himself to possible electrical shock.
Underwriters Laboratories publishes safety standards that are applicable to the light fixture industry. Underwriters Laboratories has evaluated light fixtures for double-ended lamps and has recently promulgated a revised standard which requires light fixtures for double-ended lamps to include features that would diminish the risk of shock which could occur during the installation of double-ended lamps into lamp fixtures; e.g., UL 1571 Section 57A.3.
It is an object of the present invention to provide a light fixture for a double-ended lamp which meets standard 1571 Section 57A.3 promulgated by Underwriters Laboratories.
It is an additional object of the invention to provide a light fixture for a double-ended lamp which diminishes the risk of electrical shock to one who installs a lamp while the fixture is electrically energized.
It is a further object of the invention to provide a light fixture for a double-ended lamp which prevents one who is installing the lamp from touching one end of the lamp while another end is in contact with an electrical circuit.